Rotating detonation combustors are prone to a wide range of off-design behaviors during both atmospheric and pressurized operation. The current manuscript deals with the transient mean pressure change seen in back-pressurized combustors after ignition. Using experimental high-speed pressure data acquired during this transience, we report two distinct, but overlapping, mechanisms that are well-known in deflagrative rocket combustors, but are not currently considered in rotating detonation combustors: DC shift and chugging. The former is characterized by sudden and seemingly random alterations of the time-averaged chamber pressure during operation, not unlike the same behavior observed in conventional rockets during instability onset. The latter is a low frequency instability that is inherently coupled to the reactants feed, causing significant oscillations of the mean chamber pressure. We show that these phenomena are strongly linked, where onset of chugging oscillations alter the frequency and pressure of the operating mode, which in turn produces a DC shift of the mean chamber pressure. To discern this complex interaction, we use multivariate polynomial curve-fitting, considering all the appropriate parameters to arrive at an empirical formulation that is seen to reasonably match the observed pressure transience after ignition.

旋转爆震燃烧器在常压和加压运行期间都容易出现各种不符合设计的行为。目前的手稿涉及点火后背压燃烧器中出现的瞬态平均压力变化。使用在此瞬态期间获得的实验性高速压力数据，我们报告了两种不同但重叠的机制，这些机制在爆燃火箭燃烧器中众所周知，但目前在旋转爆震燃烧器中未考虑：直流偏移和突进。前者的特点是运行期间时间平均腔室压力突然且看似随机的变化，这与在不稳定开始期间在常规火箭中观察到的相同行为没有什么不同。后者是固有地耦合到反应物进料的低频不稳定性，造成平均腔室压力的显着振荡。我们表明这些现象是密切相关的，其中突突振荡的开始改变了操作模式的频率和压力，这反过来又产生了平均腔室压力的直流偏移。为了辨别这种复杂的相互作用，我们使用多元多项式曲线拟合，考虑所有适当的参数来得出一个经验公式，该公式被认为与点火后观察到的压力瞬变合理匹配。